Odd number of walls ?

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I remember reading that Cura didn't work well with a odd number of walls as the fill gaps didn't work well. Has this bug been fixed or should I always use an even number of walls ?. Added to which does it make any difference if I always set the wall (if the part has no infil) to be a multiple of the line width. i.e. if my line width is set to 0.4 and my walls on the object are 1.2mm which is exactly 3 walls, would I still have the potential issue ? @smartavionics I think you have some very good knowledge in this, could you please advise ?, really appraicfte it

thanks

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Hello @Link, the situation hasn't changed, it's always best if the wall width is an even multiple of the line width. So a 1.2mm wide wall would print best with either a 0.6mm or 0.3mm line width. If the line width is 0.4 (or maybe just below) and the wall overlap compensation is enabled then you will get 3 full width wall lines and one that has been narrowed by the overlap compensation. Recent cura releases have a min flow setting which replaces extrusions with very low flows with travel moves and it is aimed at exactly this situation where a wall line has been overlap compensated down to almost nothing.

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for a print which has infil, i.e no think walls and the interior is filled with infil, is there any advantage to having a even or odd number or walls set in Cura ?. Or does this make no difference. Thanks

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If the print is wide enough to have infill then it doesn't really matter how many walls you have as all the walls will fit (apart from in tight corners, perhaps.) So then the considerations are different. A very small number of walls can make the infill more visible as it can distort a thin wall.

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I think when you say "even" you actually mean "integral" and when you say "odd" you mean "fractional". Right?

So if you have a nozzle of 0.4 and a line width of 0.4mm then it's true that in cura you want to have a wall width of 0.4, 0.8, 1.2, 1.6 and so on. Is that what you are talking about when you say even or odd?

If instead you have line width of 0.4 and wall width is 1.0mm cura does bad things. It might do a 0.4 shell pass followed by a 0.6mm shell pass (which might underextrude as it's harder to get a 0.6mm line through a 0.4mm nozzle) or it might do two 0.4mm walls followed by a 0.2mm wall (which I also don't think is a good idea).

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yes, this is exactly what I was checking, I always design walls to be exact multiples of the line width, for example my line width is the 0.35 and might use a wall width of 1.05, which is exactly 3 walls. but there is def and issue with odd number of walls as @smartavionics has said.

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I have conducted some experiments with walls exactly 3 and 4 line widths wide, and Cura does not seem to handle 3 lines wide correctly.

this is a wall exactly 3 lines wide, it seems to use infil rather than inner walls on the inside. you can also see some mess/fillining in the corner of the (yellow) infil part.

this is a wall of exactly 4 lines wide, see the inner is now made of actually inner walls and not from infil

I have actually always been setting my walls to even numbers multiple of line width, just didn't realise ! haha, I had been looking at the layer view and seen when setting the width to 3x line, it would mess around with infil and for some reason not use a correct line width. @smartavionics will be best place to explain why this is, but he is right that odd numbers of line width (even if they fit exactly) do not work correctly. !

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Those thin yellow "messy" lines are not walls or regular infill. They are what you get if you have the Fill Gaps Between Walls setting enabled. It rarely works well so I almost always disable that. Try disabling that, enabling the wall overlap compensation (which is also flawed but probably better used than not) and use a line width that is slightly narrower and you should get only red and green wall lines with little or no gap in the middle. Some experimentation is needed!

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